Abstract:

A communications cable is provided with a matrix tape that attenuates
alien crosstalk when cables run near one another. The matrix tape is
provided with conductive segments. The conductive segments are preferably
provided on two layers of the matrix tape. In one embodiment, the
conductive segments are attached to a film with an adhesive. A barrier
tape is preferably provided between the cable core and the matrix tape.

Claims:

1. A communication cable, comprising:a plurality of twisted pairs of
conductors;a matrix tape substantially surrounding said plurality of
twisted pairs of conductors, said matrix tape including an insulating
layer having a first side and an opposing second side, a first barrier
layer of conductive segments separated by gaps on said first side and a
second barrier layer of conductive segments separated by gaps on said
second side;a pair separator separating each of said plurality of twisted
pairs of conductors from another of said plurality of twisted pairs of
conductors, said pair separator including a plurality of frustum-shaped
separator legs joined by a central web, wherein each of said separator
legs lies approximately between one of said twisted pairs of conductors
and another of said twisted pairs of conductors.

2. The communication cable of claim 1, wherein at least one of said
frustum-shaped separator legs includes a rounded free end.

3. The communication cable of claim 1, wherein said pair separator is
produced with a clockwise rotation.

4. The communication cable of claim 1, further including a barrier tape
between said plurality of twisted pairs of conductors and said matrix
tape.

5. The communication cable of claim 4, wherein said barrier tape is
helically wound around said plurality of twisted pairs of conductors.

6. The communication cable of claim 5, wherein said matrix tape is
helically wound around said barrier tape.

7. A method of manufacturing a matrix tape for use in a communication
cable, comprising the steps of:providing a polymer substrate;attaching at
least one conductive layer to at least one side of said polymer substrate
with a corresponding adhesive layer; andkiss die cutting said at least
one conductive layer; andremoving some of said at least one conductive
layer after said kiss die cutting step to produce conductive segments on
at least one said side of said polymer substrate.

8. The method of claim 7, further comprising the step of bonding a
polyester film to said conductive layer.

9. A method of manufacturing a communication cable, comprising the steps
of:producing a matrix tape using the substeps of:providing a polymer
substrate;attaching at least one conductive layer to at least one side of
said polymer substrate with a corresponding adhesive layer;kiss die
cutting said at least one conductive layer; andremoving some of said at
least one conductive layer after said kiss die cutting step to produce
conductive segments on at least one said side of said polymer
substrate;twisting at least one pair of conductors; andwrapping said
matrix tape around said at least one pair of conductors.

10. The method of claim 9, further including the step of separating said
at least one pair of conductors from said matrix tape using an insulating
barrier tape.

11. The method of claim 9, wherein said separating step includes the
substep of helically wrapping said insulating barrier tape around said at
least one pair of conductors.

12. The method of claim 9, further including the step of jacketing said at
least one pair of conductors, and said matrix tape.

13. The method of claim 9, wherein said wrapping step is a helically
wrapping step.

14. The method of claim 13, wherein said wrapping step includes an
approximately 15.degree. angle of wrap.

15. The method of claim 13, wherein said wrapping step includes an overlap
of said matrix tape.

16. The method of claim 9, further including the step of bonding a
polyester film to said conductive layer.

17. A method of manufacturing a matrix tape for use in a communication
cable, comprising the steps of:providing a polymer substrate;attaching at
least one conductive layer to at least one side of said polymer substrate
with a corresponding adhesive layer; andremoving some of said at least
one conductive layer to produce conductive segments on at least one said
side of said polymer substrate.

18. A method of manufacturing a communication cable, comprising the steps
of:producing a matrix tape using the substeps of:providing a polymer
substrate;attaching at least one conductive layer to at least one side of
said polymer substrate with a corresponding adhesive layer;kiss die
cutting said at least one conductive layer; andremoving some of said at
least one conductive layer produce conductive segments on at least one
said side of said polymer substrate;twisting at least one pair of
conductors; andwrapping said matrix tape around said at least one pair of
conductors.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims the benefit of U.S. patent application Ser.
No. 61/112,794, filed Nov. 10, 2008. This application is incorporated
herein by reference in its entirety.

FIELD OF THE INVENTION

[0002]The present invention is related generally to telecommunications
cables and more specifically to telecommunications cables designed to
reduce crosstalk between adjacent cables.

BACKGROUND OF THE INVENTION

[0003]As networks become more complex and have a need for higher bandwidth
cabling, attenuation of cable-to-cable crosstalk (or "alien crosstalk")
becomes increasingly important to provide a robust and reliable
communication system. Alien crosstalk is primarily coupled
electromagnetic noise that can occur in a disturbed cable arising from
signal-carrying cables that run near the disturbed cable, and is
typically characterized as alien near end crosstalk (ANEXT), or alien far
end crosstalk (AFEXT). Additionally, crosstalk can occur between twisted
pairs within a particular cable, which can additionally degrade a
communication system's reliability, and is typically characterized as
near end crosstalk (NEXT), or far end crosstalk (FEXT).

[0004]One way of reducing alien crosstalk in a communication channel is to
provide a shielded cable (foiled twisted pair (F/UTP) for example)
terminated in shielded connectors. However, this solution has a much
higher cost when compared to an unshielded twisted pair (U/UTP) system
due to the higher cost of the cable and connectors, and higher labor
costs associated with terminating the shielded cable with shielded
connectors, and other installation factors. Additionally, this type of
cable can potentially increase NEXT and FEXT between pairs within a
cable. Screened and foiled twisted pair (S/FTP) cable (screened shield
around all of the pairs, and then individual foil shields around each
individual pair) reduces ANEXT and AFEXT, and also reduces NEXT and FEXT
when compared to F/UTP, but has even higher material and labor costs when
compared to F/UTP.

[0005]Alien crosstalk can also be reduced by adding a spacer between the
conductors and the cable jacket, to increase the average distance between
the conductors in adjacent cables, and thereby reduce alien crosstalk.
However, this solution increases the overall diameter of the cable which
has practical disadvantages in that such a cable typically has a larger
minimum bend radius and also, with the relatively large diameter, fewer
cables can be placed in a given conduit or cable tray.

[0006]Another option for reducing alien crosstalk is that an STP cable can
be used with the shield unterminated. Unfortunately, such a cable can
have problems with respect to electromagnetic compatibility (EMC)
requirements, both radiation and susceptibility, which can lead to alien
crosstalk particularly when there is imbalance present in the cable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is an illustration of a communication system according to one
embodiment of the present invention;

[0008]FIG. 2 is a cross-sectional view of a cable according to one
embodiment of the present invention;

[0009]FIG. 3 is a cross-sectional view of a pair separator according to
one embodiment of the present invention;

[0010]FIG. 4 is a view showing the application of barrier tape in a cable
according to one embodiment of the present invention;

[0011]FIG. 5 is a plan view of a matrix tape according to one embodiment
of the present invention;

[0015]Referring now to the drawings, and more particularly to FIG. 1,
there is shown a communication system 20, which includes at least one
communication cable 22, connected to equipment 24. Equipment 24 is
illustrated as a patch panel in FIG. 1, but the equipment can be passive
equipment or active equipment. Examples of passive equipment can be, but
are not limited to, modular patch panels, punch-down patch panels,
coupler patch panels, wall jacks, etc. Examples of active equipment can
be, but are not limited to, Ethernet switches, routers, servers, physical
layer management systems, and power-over-Ethernet equipment as can be
found in data centers/telecommunications rooms; security devices (cameras
and other sensors, etc.) and door access equipment; and telephones,
computers, fax machines, printers and other peripherals as can be found
in workstation areas. Communication system 20 can further include
cabinets, racks, cable management and overhead routing systems, and other
such equipment.

[0016]Communication cable 22 is shown in the form of an unshielded twisted
pair (UTP) cable, and more particularly a Category 6A cable which can
operate at 10 Gb/s, as is shown more particularly in FIG. 2, and which is
described in more detail below. However, the present invention can be
applied to and/or implemented in a variety of communications cables, as
well as other types of cables. Cables 22 can be terminated directly into
equipment 24, or alternatively, can be terminated in a variety of plugs
25 or jack modules 27 such as RJ45 type, jack module cassettes, and many
other connector types, or combinations thereof. Further, cables 22 can be
processed into looms, or bundles, of cables, and additionally can be
processed into preterminated looms.

[0017]Communication cable 22 can be used in a variety of structured
cabling applications including patch cords, backbone cabling, and
horizontal cabling, although the present invention is not limited to such
applications. In general, the present invention can be used in military,
industrial, telecommunications, computer, data communications, and other
cabling applications.

[0018]Referring more particularly to FIG. 2, there is shown a transverse
cross-section of cable 22, taken along section line 2-2 in FIG. 1. Cable
22 includes an inner core 23 with four twisted conductive wire pairs 26
that are separated with a pair separator 28. A cross-section of pair
separator 28 is shown in more detail in FIG. 3, which shows dimensions of
one embodiment of the pair separator first in inches and second (in
brackets) in millimeters. In a preferred embodiment, pair separator 28 is
produced with a clockwise rotation (left hand lay) with a cable stranding
or lay length of 3.2 inches. Pair separator 28 can be made of a plastic,
such as a solid fire retardant polyethylene (FRPE), for example.

[0019]A wrapping of barrier tape 32 surrounds inner core 23. Barrier tape
32 can be helically wound around inner core 23 as shown in FIG. 4, with
an approximate 15°±10° angle of wrap. In a preferred
embodiment barrier tape 32 can be a polypropylene foam, for example, with
a 1.5 inch width and a 0.005 inch thickness. As shown in FIG. 2, the
twisted pair conductors extend beyond pair separator 28 to create an
outer diameter of inner core 23 of approximately 0.2164 inches, which has
a circumference of 0.679 inches. The barrier tape 32 therefore wraps
around inner core 23 slightly more than twice, and there are two
applications of barrier tape 32 (as shown in FIG. 4) which gives a total
approximate thickness for barrier tape 32 of 0.020 inches (however, other
thicknesses are possible such as 0.005 to 0.0030 inches).

[0021]Matrix tape 34 (see particularly FIGS. 5-7) is helically wrapped
around barrier tape 32, as is shown in FIGS. 2 and 4, with an
approximately 15° angle of wrap, and approximately 25% overlap,
for example. According to one embodiment, matrix tape 34 is "kiss" die
cut to produce conductive segments 36 on either side of tape 34. FIG. 7
illustrates a cross-section of matrix tape 34 in a section of the tape
where there are conductive segments 36 on either side; or in other words,
a cross-section of matrix tape 34 prior to the kiss die cutting. The
material remaining between conductive segments 36 after kiss die cutting
is the center polyester film substrate, and perhaps some adhesive
residue. The box at the top of FIG. 7 shows the overall thickness of a
polyester-aluminum laminate, along with the thicknesses of the polyester
and aluminum layers that make up the laminate. Also included in the
laminate, though not shown in the chart, is a thin layer of adhesive,
having a thickness of about 0.0001''. FIGS. 5, 6 and 7 show dimensions
for one embodiment of a matrix tape according to the present invention,
first in inches and second (in brackets) in millimeters. Dimensions
marked "T.S.C. Typ" reflect the theoretical dimensions if the corners
were sharp instead of rounded. FIG. 6 is a detail view of detail "A" of
FIG. 5. The "radius" ("R") of the rounded corners is given in FIG. 6.

[0022]Cable 22 also can include an outer insulating jacket 38. Outer
insulating jacket 33, can be made of flame retardant polyvinyl chloride
(FRPVC), and can be 0.015 inch thick (however, other thicknesses are
possible). The overall diameter of cable 22 can be nominally 0.302 inch,
for example; however, other thicknesses are possible.